Hi guys, I am definitely late to the party, but here is my Airport Layout designer:
Mine is PowerPoint based, which I find easier to use since objects are easy to place, move around and resize.
There is some complexity involved since you will have to manually do what the game would do automatically (like placing intersections), so I have given some instructions in the file. If any more help is required, let me know.
Although the life of this may be short lived as we expect the game to come out within a couple of weeks, not necessarily. I think this can always be helpful for someone whi has access to a computer, but not necessarily the one on which the game is installed (like when travelling).
And I have not yet used this to make my own designs yet, so I welcome any feedback from the community.
Edit: I just started designing my first airport, and I realised that the canvas space that I have is hilariously tiny. About 10 gates in, and I have no space to finish the terminal design.